title: Synthesis and spectroscopic properties of fused-ring-expanded aza-boradiazaindacenes.
abstract: A series of fused-ring-expanded aza-boradiazaindacene (aza-BODIPY) dyes have been synthesized by reacting arylmagnesium bromides with phthalonitriles or naphthalenedicarbonitriles. An analysis of the structure-property relationships has been carried out based on X-ray crystallography, optical spectroscopy, and theoretical calculations. Benzo and 1,2-naphtho-fused 3,5-diaryl aza-BODIPY dyes display markedly red shifted absorption and emission bands in the near-IR region (>700 nm) due to changes in the energies of the frontier MOs relative to those of 1,3,5,7-tetraaryl aza-BODIPYs. Only one 1,2-naphtho-fused aza-BODIPY of the three possible isomers is formed due to steric effects, and 2,3-naphtho-fused compounds could not be characterized because the final BF(2) complexes are unstable in solution. The incorporation of a -N(CH(3))(2) group at the para-positions of a benzo-fused 3,5-diaryl aza-BODIPY quenches the fluorescence in polar solvents and results in a ratiometric pH response, which could be used in future practical applications as an NIR "turn-on" fluorescence sensor.
authors.affiliation: State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, China.
authors.forename: Hua
authors.initials: H
authors.lastname: Lu
authors.forename: Soji
authors.initials: S
authors.lastname: Shimizu
authors.forename: John
authors.initials: J
authors.lastname: Mack
authors.forename: Zhen
authors.initials: Z
authors.lastname: Shen
authors.forename: Nagao
authors.initials: N
authors.lastname: Kobayashi
mesh_terms: D000327:Adsorption; D001896:Boron Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D018360:Crystallography, X-Ray; D055664:Electrochemical Techniques; D008968:Molecular Conformation; D011789:Quantum Theory; D013055:Spectrophotometry, Infrared
chemical_list: C095489:4,4-difluoro-4-bora-3a,4a-diaza-s-indacene; D001896:Boron Compounds